Ultra-high vacuum compatible full metal atom beam shutter for optical lattice clocks

We developed a shutter driven by a solenoid to switch on/off the atomic beam of optical lattice clocks developed at KRISS [C. Y. Park et al., Metrologia 50, 119 (2013), S. Lee et al., New J. Phys. 18, 033030 (2016), H. Kim et al., Jpn. J. Appl. Phys. 56, 050302 (2017), and H. Kim et al., Metrologia 58, 055007 (2021)]. The shutter design was focused on long lifetime and compatibility with an ultra-high vacuum (UHV) environment. Thus, the solenoid was designed to be easily installed and removed from the air-side of a CF flange of the shutter. The flag in the vacuum-side moves only with the simple spring action of a sheet of a metal plate without any frictional movement of mechanical parts. All parts in the vacuum-side were made of metals (stainless steel and pure iron) to be baked over the temperature of 200 °C for UHV. The flag head of the shutter displaces up to 10 mm (5 mm) with a response time of 50 (30 ms) and 80 ms (10 ms) for the opening-action and the closing-action, respectively. The lifetime was tested up to 6 × 10⁶ cycles with no performance degradation. We expect the actual lifetime to be much longer than this by virtue of its friction-free design.